/*
  将下面异步代码使用 Promise 的方法改进
  尽量用看上去像同步代码的方式
  setTimeout(function () {
    var a = 'hello'
    setTimeout(function () {
      var b = 'lagou'
      setTimeout(function () {
        var c = 'I ♥ U'
        console.log(a + b +c)
      }, 10)
    }, 10)
  }, 10)
*/

new Promise(resolve => {
  const a = 'hello'
  resolve(a)
})
.then((a) => {
  const b = 'lagou'
  return `${a} ${b}`
}).then(ab => {
  const c = 'I ❤ U'
  return `${ab} ${c}`
}).then(abc => console.log(abc))